1. Field of the Invention
This invention relates to encryption techniques for streaming media.
2. Description of the Related Technology
Digital content such as video, audio and multimedia digital files are usually quite large and there may be a long transmission delay before a recipient is able to see or hear the content of such files when transmitted to him, particularly over the internet where bandwidth at some point in the transmission channel may be limited. The technique of streaming media files addresses this problem and allows the recipient to commence viewing video or listening to audio long before the media file has been completely received by him. A video may be displayed and audio played as soon as there is sufficient data in the buffer of the recipient station.
As with other digital files there are a number of applications where it is highly desirable for a streaming media file to be encrypted. Usually the content will be subject to copyright and encryption will be desired to supplement the legal protection. The encryption of streaming media poses additional problems to those encountered when a complete file is encrypted, transmitted and decrypted before use by the recipient. In practice most digital data transmission over a distance is conducted using packet technology. Therefore the encryption of streaming media requires packet by packet encryption and decryption if the advantages of streaming are to be preserved.